Fungal infections of the skin are also known as ‘mycoses’. They are common and generally mild. In sick or otherwise immune-suppressed individuals, however, fungi can sometimes cause serious disease. Fungal infections in humans range from superficial, i.e., skin surface to deeply invasive type or disseminated infection.
In general, superficial fungal infections (also known as cutaneous mycosis) can affect the outer layers of skin, nails and hair. The main groups of fungi causing superficial fungal infections are dermatophytes (tinea), yeasts, e.g., candida, malassezia, piedra, etc. and moulds. These infections include dandruff/seborrheic dermatitis (D/SD), ringworm, onychomysis, intertrigo, and those in psoriasis amongst others.
Seborrheic dermatitis is a common, chronic, superficial skin disorder causing scaly, itchy, red skin on the scalp, eyebrows, nasolabial creases, lips, ears, sternal area, axillae, submammary folds, umbilicus, groins, and gluteul crease. The disease is characterized by many shapes, sizes, and surface textures and is often crust-like, yellowish, and accompanied by itching. Seborrheic dermatitis is one of the leading causes of stubborn dandruff and occurs in all age groups. This condition primarily affects the sebaceous cysts present in the skin.
Currently, fungi of the genus Malassezia are believed to be the most likely responsible agents for causing dandruff (Dawson T. L., J. Investig. Dermatol. Symp. Proc. (2007), 12:1519). Most cases of seborrhoeic dermatitis likely involve an inflammatory reaction to the proliferation of the yeast Malassezia. These fungi are highly dependent on external lipids for in vitro growth (Chen T. A. and Hill P. V., Vet Dermatol, (2005), 16:4). Further, the inability to synthesize fatty acids may be complimented by the presence of multiple secreted lipases to aid in utilizing host lipids. Consequently, these fungi metabolize triglycerides present in sebum through these lipases resulting in lipid by-products. Penetration of the top layer of the epidermis, the stratum corneum, by these lipid by-products results in an inflammatory response in susceptible persons, which disturbs homeostasis causing erratic cleavage of stratum corneum cells, further leading to dandruff and seborrheic dermatitis.
The most common treatment of fungal infections is the topical application of antifungal agents that reduce the level of Malassezia on the scalp. Maintaining the scalp clean is mandatory for sufferers of seborrheic dermatitis. Use of effective anti-dandruff shampoos is, therefore, a significant way of preventing this condition.
Typically, the antifungal agent is applied to the scalp as a component of a shampoo or other hair care composition. The disadvantage of such shampoo formulations is that during normal usage the formulation does not remain on the scalp for a period of time sufficient to allow the antifungal agent to achieve its maximal therapeutic effect (Ralph M. Trüeb, JDDG, (2007), 5:356). These are designed to be applied, for example, in the shower or bath, and shortly thereafter rinsed off with water. Typically, the application instructions for such shampoos suggest that the formulation be removed after 3-5 minutes.
One of the antifungal agents, ketoconazole is among the most potent and widely used in anti-dandruff shampoos. However, the exposure time of shampoo is less, due to which the efficacy is poor and relapse rates are higher.
In the past we found that, fatty acids and their derivatives (e.g. methylated and hydroxyl fatty acids) are known to possess antibacterial and antifungal activity as they target the cell membrane leading to increase in membrane fluidity (Douglas and Marshalland, “Antimicrobials in Food”, 3rd edition, CRC Press 2005 Pg. no. 327-360).
In context to another review, the pelargonic and capric acid on Microsporum gypseum were found to be effective when tested in-vitro cell culture (Chandeganipour and Haims, “Mycoses”, 2001, Volume 44, Issue 3-4, pages 109-112). Similar reports were found with reference to Candida albicans when exposed to monoesters of glycerides of capric (C10 saturated medium chain fatty acid) (Bergsson et al., Antimicrobial agents and Chemotherapy, 2001, Vol 45 pg. no. 3209-3212).
U.S. Patent Application 2010/0016271 discloses hair conditioning compositions comprising cationic surfactant, triglyceride oil and an anti-dandruff agent. These compositions contain triglyceride oil, which are fatty acid esters of glycerol, and hence act as nutrients and aid in the growth of the fungus. These compositions contain fatty material up to 10% having carbon chains from 8 to 30 carbon atoms.
U.S. Pat. No. 5,624,666 describes shampoo compositions containing anionic surfactants, cationic polymers, and zinc pyridinethione as an anti-dandruff agent. It describes that conditioning agents such as silicone fluids can optionally be incorporated into the compositions therein. Head & Shoulders® Dandruff Shampoo Plus Conditioner is an example of a marketed product which provides both anti-dandruff and conditioning benefits upon application of the shampoo to hair. The exposure time of shampoos is less than required for effective antifungal activity, hence relapse rates are higher.
U.S. Pat. No. 7,547,752 refers to synergistic combination of an anti-dandruff agent with conjugated linoleic acid for prevention or treatment of dandruff and scalp itching.
European Patent No. 1923043A1 discloses cationic conditioning agents and an anti-dandruff agent with surfactants, silloxanes and natural and lipophillic oily components and their derivatives for the treatment or prevention of dandruff with conditioning.
European Patent No 0116439 discloses fatty acids like petroselinic and linoleic and saturated and unsaturated derivatives which alleviate dandruff and stimulate hair growth.
Commercially available formulations for the treatment of dandruff are leave-on hair formulations such as hair oils, styling gels, etc. These formulations also contain anti-dandruff or antifungal agents. Conventional leave-on formulations, especially oils or creams, contain fatty acid or their esters as an essential ingredient. These fatty acid and esters aid the growth of dandruff-causing fungus (Malassezia furfur) and work as nutrients.
Accordingly, there remains a need for an antifungal composition that provides improved cleansing and optimal anti-dandruff efficacy. The present invention addresses this need by providing topical compositions having antifungal agents and is devoid of fungus nutrients.